The present invention relates to a phase detection device, a dial type detection device, and a phase detection method.
In many electronic devices, a dial type detection device has been used as means for a user to input an operation command. The dial type detection device comprises a rotatable dial and a phase detection device for detecting a rotation phase of a dial. The electronic device derives a rotation direction and a rotation angle of the dial based on two phases (Generally, the phase is different from each other by π/2.) which the phase detection device outputs, and based on those information, performs, for example, a cursor movement on an image display screen, a display content change (for example, an increment or a decrement of displayed numeric values or the like), or other processes.
By installing the phase detection device in a lever (A traveler is installed thereto similar to a case where a rotator is installed in the dial which is mentioned later.) which performs a straight line movement, a movement direction and an amount of movement of the control lever can be detectable. The electronic device inputs the operation command from the user through the control lever incorporating the phase detection device. An operation direction of the control lever and a detection method of the amount of movement are similar to a method of the dial type detection device mentioned later. The following discussion is described by taking an example of the dial type detection device.
The phase detection device of a prior art is described using FIGS. 6-14. As the phase detection device of the prior art, the phase detection devices which employ a magnetic system, an optical system, and a mechanical system are proposed.
FIG. 6 is a block diagram showing a configuration of a phase detection device of the prior art 1 incorporated in the dial type detection device. The dial type detection device is mounted on an operation panel of the electronic device. The phase detection device of the prior art 1 employs the magnetic system. In FIG. 6, symbols 20a and 20b are magnetic flux detecting sections and symbol 31 is a power supply section. A multi-pole magnetized magnet of a ring shape (rotor) is fixed to a bottom surface of the dial that the user rotatably operates, along the periphery or the bottom surface. The magnetic flux detecting sections 20a and 20b are always supplied a power from the power supply section 31, detects a magnetic field (magnetic flux density) which the magnet fixed to the dial generates, and generates two binarized signals, the phase of which is different from each other by π/2 (Referred to as an A phase output voltage or an A phase output signal, or a B phase output voltage or a B phase signal.), respectively.
FIG. 8 is a time chart showing the A phase output voltage that the magnetic flux detecting section 20a outputs, and the B phase output voltage that the magnetic flux detecting section 20b outputs. A microcomputer of the electronic device receives the A phase output voltage and B phase output voltage, the phase of which is different from each other by π/2, and based on which phase is advanced, can detect the rotation direction of the dial. By counting a change in the amount of the phase of the A phase output voltage and/or the B phase output voltage, the rotation angle of the dial can be derived. In a patent document 1 (JP-A-57-175260), “a rotation direction detection device of the prior art”, which employs a pickup coil, is described.
For example, by inputting either of the binarized A phase output voltage and B phase output voltage which the phase detection devices output (the phase is different from each other by π/2) into a clock input terminal of a D flip-flop, and inputting the other into a data input terminal, the D flip-flop outputs a rotation direction detection signal (For example, it is Q output signal and a value 0 or 1 indicates a rotation direction.). Moreover, by inputting the A phase output voltage (or the B phase output voltage) into a clock input terminal of an UP/DOWN counter, and inputting the rotation direction detection signal into an UP/DOWN switching terminal, a count value of the UP/DOWN counter indicates the rotation direction and the rotation angle of the dial type detection device. The electronic device performs a predetermined process based on information about the rotation direction and the rotation angle of the dial type detection device.
The phase detection device of a prior art 2 incorporated in the dial type detection device is described using FIG. 6. The phase detection device of the prior art 2 employs the optical system. In FIG. 6, symbols 20a and 20b are photo interrupters, in which diodes and photo transistors are positioned to oppose on both sides of a slit, (Other optical sensors, such as a photo reflector may be used.), and symbol 31 is a power supply section. A ring-shaped plate (rotor) provided with light shield sections (typically black stripes) and transparent sections extending radially are alternately arranged around the perimeter is fixed to the bottom surface of the dial that the user rotatably operates. The ring-shaped plates inserted in the slits of the photo interrupters 20a and 201b pass through or interrupt the light which the light emitting diode emits towards the photo transistor. The photo interrupters 20a and 20b generate two binarized signals (A phase output voltage and B phase output voltage), the phase of which is different form each other by π/2, respectively.
The phase detection device of a prior art 3 incorporated in the dial type detection device is described using FIG. 7. The phase detection device of the prior art 3 employs the mechanical system. In FIG. 7, symbols 40a and 40b are switches, each of which has a mechanical actuator and a switching mechanism, symbols 41a and 41b are resistors, and symbol 31 is a power supply section. A ring-shaped plate (rotor), in which irregularities are formed along the periphery, is fixed to the bottom surface of the dial that the user rotatably operates. Switches 41a and 41b are arranged so that contact points may be short-circuited according to a rotation angle of the dial, and timing when the contact points are short-circuited may be different from each other by π/2. A junction point between the resistor 41a and the switch 40a, and a junction point between the resistor 41b and the switch 40b output two binarized signals (A phase output voltage and B phase output voltage), the phase of which is different from each other by π/2, respectively.
In recent years, in such phase detection devices, the needs from the market for reducing the power consumption has been rapidly increased for the purpose of equipping them in portable equipment or the like. As an approach for reducing the power consumption of the phase detection device, other than achieving a low voltage drive of the phase detection device, there is an approach that, when the user does not operate the dial type detection device for a predetermined time, the power supply to the phase detectors of the phase detection devices (symbols 20a and 20b in FIG. 6, resistor 41a and switch 40a, resistor 41b and switch 40b in FIG. 7) is changed from an always energized mode to an intermittently energized mode (Referred to as sleep function.) (Referred to as sleep mode.).
FIG. 9 is a block diagram showing a configuration of a phase detection device of a prior art 4 of the mechanical system which has the sleep function. FIG. 10 is a time chart showing a signal waveform of each section of the phase detection device of the prior art in FIG. 9. The phase detection device of the prior art 4 is installed in the dial type detection device. The phase detection device of the prior art, comprises: a sleep detection function for detecting that the rotor has not moved for a certain period of time; and a power activation condition detection function wherein a first phase detector (resistor 41a and switch 40a) or a second phase detector (resistor 41b and switch 40b) detects the rotor has moved in the sleep mode.
In FIG. 9, symbol 31 is a power supply, symbol 30 is a switch for the power supply, and symbol 91 is a control section. A resistor 41a and a switch 40a configure the first phase detector, and a resistor 41b and a switch 40b configure the second phase detector. The control section 91 has first-fourth memory sections 10a-10d (each of them is a D flip-flop.), a decoder 61, and a state control section 60. The decoder 61 has exclusive OR gates 12a and 12b, and an OR gate 63.
The first-fourth memory sections 10a-10d and the decoder 61 perform the power activation condition detection function, wherein the first phase detector (resistor 41a and switch 40a) or the second phase detector (resistor 41b and switch 40b) detects that the dial or the like (rotor) has moved in the sleep mode. The state control section 60 receives the A phase output signal (signal outputted from an A junction point between the resistor 41a and the switch 40a), and the B phase output signal (signal outputted from a B junction point between the resistor 41b and the switch 40b), and performs the sleep detection function for detecting that the rotor has not moved for a certain period of time, The state control section 60 makes the phase detection device shift to the sleep mode from the always energized mode when the sleep detection function works. When the power activation condition detection function works, it makes the phase detection device shift to the always energized mode from the sleep mode. The switch for the power 30 always brings a current flowing from the power supply 31 to the first phase detector and the second phase detector into conduction in the always energized mode, intermittently brings it into conduction in the sleep mode, and cuts off it in other modes.
In FIG. 10, symbol A is the A phase output signal and symbol B is the B phase output signal. Symbols 10a-10d, 12a, 12b, 63, and 60 are the output signals of blocks with the same symbol, respectively. Symbols ST and SC are an ST signal and an SC signal which are mentioned later, respectively.
In FIG. 10, first, the state control section 60 is in the always energized mode. By the user rotating the dial (rotor) in a certain direction until a certain time, the B phase output signal continuously changes following to the A phase output signal with a phase delay by π/2. From a certain time to a time ts (predetermined time), the sleep detection function works based on both the A phase output signals and the B phase output signals being unchanged, the state control section 60 shifts to the sleep mode from the always energized mode, and makes the output signal ST High (it is High in the sleep mode, and Low in the always energized mode. Referred to as ST signal.). The first memory section 10a and the third memory section 10c latch the A phase output signal and the B phase output signal (both are binary) just before shifting to the sleep mode with a rising edge of the ST signal. The first memory section 10a and the third memory section 10c store the A phase output signal and the B phase output signal until the next rising edge of the ST signal arrives, and input those signals into the exclusive OR gates 12a and 12b, respectively.
Subsequently, based on a command from the state control section 60, the switch for the power 30 cuts off the power supply to the two phase detectors (resistor 41a and switch 40a, resistor 41b and switch 40b). Therefore, the A phase output signal and the B phase output signal become Low. Subsequently, the commands are sent to the switch for the power 30 for every predetermined period from the state control section 60, and the switch for the power 30 supplies the power to two phase detectors for every predetermined period. The state control section 60 intermittently outputs a scanning signal SC (Hereinafter referred to as SC signal.) only for a sleep period. The second memory section 10b and the fourth memory section 10d latch the A phase output signal and the B phase output signal (both are binary) with a rising edge of the SC signal. The second memory section 10b and the fourth memory section 10d store the A phase output signal and the B phase output signal until the next rising edge of the SC signal arrives, and input those signals into the exclusive OR gates 12a and 12b, respectively.
The output signal of the exclusive OR gate 12a is a logic change judging result between the A phase output signal before shifting to the sleep mode and the A phase output signals at each scanning time ts (1)−ts (n). The output signal of the exclusive OR gate 12b is a logic change judging result between the B phase output signal before shifting to the sleep mode and the B phase output signals at each scanning time. The OR gate 63 receives the output signals of the exclusive OR gates 12a and 12b, and outputs a logical sum of them. When a value of either the A phase output signal or the B phase output signal changes from a value just before changing to the sleep mode, the output signal of the OR gate 63 becomes High.
Since a state between the time ts and the time ts (1) is in a state where a first scanning signal has not arrived yet, values which the second memory section 10b and the fourth memory section 10d latch are not correct, and outputs of the OR gate 63 during this period can not be used as it is. The state control section 60 does not use the output signals of the OR gate 63 until the first scanning signal is outputted.
Hereafter, the process of the power activation condition detection after the time ts (1) until a time tw when it moves out from the sleep period is described.
With the rising edge of the SC signal at the time ts (1), the A phase output signal and the B phase output signal are latched by the second memory section 10b and the fourth memory section 10d. The data output of the second memory section 10b is inverted from Low to High, and since the output of the exclusive OR gate 12a is Low and the output of the exclusive OR gate 12b is still Low, the output of the OR gate 63 becomes Low and the sleep period is maintained.
At a time ts (x), when only either the A phase output signal or the B phase output signal in the scanning time (in FIG. 10, B phase output signal) changes from the A phase output signal or the B phase output signal just before shifting to the sleep mode, the output of the exclusive OR gate 12b becomes High, and the output of the OR gate 63 changes to High. The state control section 60 receives an output signal (power activation condition detection signal is active at High) of the OR gate 63. The state control section 60 changes from the sleep mode to the always energized mode. The state control section 60 energizes the switch for the power 30, and the switch for the power 30 always energizes two phase detectors (switch and pull-up resistor).
Not having such contact wear as the mechanical system because of a non-contact system, the phase detection device of the magnetic system is highly reliable, and is low in power dissipation and in cost as compared to the optical system.
As the phase detector of the magnetic system, a Hall device, magnetoresistive elements, ICs, in which even the function for discriminating the output voltage of the Hall device with a certain fixed threshold value and outputting the binarized output signal is integrated (hereinafter referred to as Hall IC), or the like are employed.
In order that these Hall device and Hall IC may consume a current of several mA as an operating current, it becomes a large burden to use them in the state of always supplying the power against battery capacity of a portable device equipped with these elements.
However, in the magnetic system, when using the phase detector by intermittently supplying the power thereto, the problem which has not been found in the mechanical system would be generated.
FIG. 11 shows a configuration of the Hall IC which has been largely employed as a common phase detector. In FIG. 11, symbol 80 is a Hall device for detecting a magnetic flux density (magnetic field), symbol 81 is an amplifier for amplifying the magnetic flux density detection voltage of the Hall device, and symbol 82 is a binarizer having hysteresis (Schmitt trigger type buffer). FIG. 12 is an example of a characteristics chart showing the relationship between an input magnetic flux density of the Hall IC (horizontal axis), and a magnetic flux detection voltage (vertical axis).
The Hall IC has a hysteresis characteristic so that a stable logical output signal (binary output signal) to the magnetic flux density may be outputted. That is, the Hall IC sets a dead zone to the input magnetic flux density so that an output signal may not be made to respond to a change in a very small magnetic flux density with ease (Referred to as a state holding function.).
However, since the Hall IC does not have a state holding function corresponding to the intermittent drive operation at a power supply terminal and does not have a power supply reset function, when turning the power on in the state where the magnetic flux whose level is within upper and lower threshold values of the hysteresis of the input magnetic flux density (Hereinafter referred to as hysteresis region.) is inputted, an initial value of the Schmitt trigger type buffer becomes an indefinite state, and the magnetic flux detection voltage also becomes an indefinite state. During the conduction period, this indefinite state permanently keeps that state until a magnetic flux input level exceeding the upper and lower hysteresis threshold values arrives.
FIG. 13 is a chart showing the relationship between the input magnetic flux density (the vertical axis is input magnetic flux density) and the output voltage waveform (the vertical axis is voltage) of the phase detector (the horizontal axis is time), when assuming that the change of the magnetic flux density roughly draws a sign curve to the rotation angle or the movement distance.
Slash portions of the output voltage waveform in the figure are output voltage indefinite regions corresponding to a hysteresis region. After stopping the rotor or the traveler in the hysteresis region, when the power supply of the phase detector is cut off once and the power supply is turned on again, the phase detector does not necessarily output the same detection output voltage as before the power supply cutoff.
Parts (a) and (b) of FIG. 14 are waveform charts of the A phase output signal and the B phase output signal of the phase detector, (the vertical axis is output voltage of each phase detector, and the horizontal axis is time), when assuming that the phase detector of the magnetic system is intermittently energized.
In part (a) of FIG. 14, at X point or Z point, or X′ point or Z′ point, no indefinite region exists in both the A phase output signal and the B phase output signal. By taking measures against the phase detection device so that the rotor may not stop within the indefinite region by any means, when making the rotor always stop at X or Z, or X′ or Z′ point, the problem of the indefinite output by the intermittent power supply of the phase detector described above can be avoided. However, in an actual phase detection device, to take such measures is mechanically difficult. When an unexpected operation is made by the user under an actual operating condition, for example, when the rotor is left within the indefinite region for a long time, incorrect power activation condition detection signals are continuously outputted from the phase detector, and such problems that remaining capacity of the battery of the device equipped with the phase detection device is exhausted or the like may be generated.
In order to avoid this problem, irrespective of where a stop point of the rotor or the traveler may exist, it is needed to accurately judge whether the rotor or the traveler has moved or not.
In part (a) of FIG. 14, assuming now that the rotation angle or the movement distance comes into a standstill at the point of W in the figure for a certain period of time, and it enters the sleep mode at this point. In the case of this magnetic system, when an intermittent operation is performed, as for the B phase output signal shown in the lower chart, even in a state where a position coordinate of the rotor or the traveler is not moved, it becomes indefinite which output voltage, that is, High or Low detection output, may appear in the intermittent operation. When only the B phase output signal changes, it cannot be judged whether it is because the rotor or the traveler has actually moved or because of the indefinite output according to the intermittent operation. Similarly, when it also enters the sleep mode at the point of W′ in part (a) of FIG. 14, when only the A phase output signal changes, it cannot be judged whether it is because the rotor or the traveler has actually moved or because of the indefinite output according to the intermittent operation.
Therefore, the same method as the power activation condition detection method in the phase detection device according to the prior art mechanical system has not been applied to the phase detection device of the magnetic system.